add by mixing or blending on or attaching; "work in the butter and the dough will get the right consistency"; "In his speech, the presidential candidate worked in a lot of learned words"
excite to an abnormal condition, of chafe or inflame; "Aspirin irritates my stomach"
excite to some characteristic action or condition, such as motion, contraction, or nervous impulse, by the application of a stimulus; "irritate the glands of a leaf"